1. Field of the Invention
This invention relates generally to equipment for in-situ machining and particularly to orbital machining apparatus for repairing crankshafts.
2. Brief Description of the Background Art
It has been appreciated that while the cost to transport repair personnel to the site of the breakdown of a large scale internal combustion engine, such as a large marine diesel engine, may be high, it is only a fraction of the cost of dismantling a crankshaft, having it transported to a workshop, returning the crankshaft, and reassembling it. H. F. de Jonge, "In Situ Crankshaft Repair," Diesel and Gas Turbine Worldwide, April 1983. As a result, various apparatus have been developed for the on-site machining of damaged crankshafts and particularly for the repair of the crank pins of those crankshafts. Included in this kind of machinery are the orbital-type machines which attach to the crankshaft and include a machining head which orbits about the damaged part to remachine the part.
With conventional equipment, it may not be possible to accurately machine the fillet between the crank pin and the crank web. This is because the conventional machining equipment attaches to the crank pin in a way that makes the fillet inaccessible. This limits the usefulness of these devices and may require additional, subsequent machining operations.
In addition, with conventional equipment, it is not always possible to accurately position the orbital tooling head with respect to the crank pin being machined. Once the apparatus is positioned or set on the crankshaft, adjustment thereafter is often difficult or impossible.